When the packet data is forwarded to a terminal via a communication network (hereinafter, abbreviated as “network” in the present application), it is desirable to perform QoS (Quality of Service) control in a wireless base station. The reason is because a communication bandwidth (communication speed) and an allowable amount of delay required when transmitting the packet data are different in accordance with types of the forwarded packet data. For example, when the packet data is video streaming data, the communication bandwidth has to be greater than an encoding rate indicating a data size per unit reproduction time of the video streaming data. When the packet data is voice data for voice communication, the allowable amount of delay needs to be less than several hundred milliseconds. On the other hand, when the packet data is electronic mail data, the communication bandwidth and the allowable amount of delay are not specified in particular.
Especially, when the packet data is forwarded to the terminal from the wireless base station via the network, the communication bandwidth and the delay amount greatly vary by various factors such as a radio wave interference, a change in radio wave intensity, and the like because of characteristics of a wireless access. Therefore, QoS control is very important.
As an example, patent document 1 discloses a technology for a packet forwarding device. The packet forwarding device includes a queue provided for each of a plurality of services, means for sorting the packet to be forwarded to each queue, and means for performing wireless transmission based on a priority value calculated for each queue.